1. Technical Field
The present invention relates to vehicle tires and particularly to a method and apparatus for determining the start of hydroplaning of the tire due to the increased volume of water and pressure between the tire and road surface.
2. Background Information
When a vehicle tire travels along a wet road, a film of water is formed between the tire and road surface at the area of contact or at the footprint of the tire. This can result in a hydroplaning effect on the vehicle or tire when the tread pattern of the tire is insufficient to disperse the amount of water accumulating between the tire and road surface. This hydroplaning effect on a vehicle is one of the many factors tire manufacturers consider when designing tires and in particular, the tread pattern thereof, which is designed to disperse as much water as possible while providing the other features to the tire such as wear, cornering, braking, etc.
Various tests have been designed to determine the hydroplaning effect on a particular tire tread pattern and to quantify the tire performance. Heretofore, most of these tests were performed on outdoor test tracks with an actual production tire. Such testing is expensive and time consuming. In order to avoid these expensive outdoor tire test procedures, various indoor tire test equipment has been developed such as shown in U.S. Pat. Nos. 4,095,464, 4,593,557, 5,174,151, 5,347,588, and 5,723,768. All of these indoor test apparatus have various mechanisms for placing a load on the tire and for viewing the footprint of the tire at the contact patch or area with the road surface and disclose methods for analyzing the data to ascertain the effectiveness of the particular tire tread pattern being tested for various driving factors including hydroplaning. U.S. Pat. No. 5,723,768 uses a wedge of water beneath the tire and by measuring the natural vibration of the tire is able to evaluate the possibility of the effect of water on the hydroplaning of the tire.
The present invention provides a relatively simple and inexpensive test apparatus and method for determining the susceptability of a particular tire tread pattern to hydroplaning. The test apparatus of the present invention includes a frame that supports the tire wheel assembly above a simulated road surface or test surface and supplies a load of desired amount to the axle/spindle of the tire wheel assembly.
The spindle of the test apparatus of the present invention can be allowed to rotate freely or be fixed in place and a fluid such as water, is applied at high pressure through a nozzle against the leading portion of the tire at the area of contact with the test surface. Measurements are taken of the load applied on the tire and the amount of water applied thereto until the tire begins to spin or lifts off the test surface. This data provides an indication of the start of hydroplaning.
Another aspect of the invention enables the test apparatus and method to compare the collected data of the load applied to a tire and the amount of fluid pressure from the injection nozzle required to begin lifting the tire off the road contact surface or start of tire rotation against results of a standard tire tested under actual road conditions to provide a comparison therebetween.
Another feature of the invention is the ability to control the environment in which the tire is being tested such as the ambient temperature, surface conditions, and tire pressure. Also, various forces such as camber can be placed on the tire.
Still another feature of the invention is the ability to test quickly many designs, control test conditions, vary load, vary inflation pressure, run repeated tests without encountering unsatisfactory environmental test conditions such as wind, evaporation, and vehicle speed as experienced in an outdoor tire test environment.
Another aspect of the invention is the ability to use high speed video equipment, cameras, etc. for recording the tire footprint contact by providing a transparent test surface as the pressurized water is being applied thereto and increased to an amount of inducing full hydroplaning for further analyzing the effect of the water and dispersion pattern thereof through the tire tread pattern.
Still another advantage of the invention is the use of a nozzle having a width wider than the actual width of the test tire tread which is capable of delivering a sufficient volume of water under sufficient pressure to create a hydroplaning condition, and directing the stream of high pressure water at various angles on the tire tread to analyze the effect of the water dispersion pattern, the possibility of lateral hydroplaning, and the effect of the water on the tire during cornering or other driving conditions.
The foregoing advantages, construction, and operation of the present invention will become readily apparent from the following description and accompanying drawings.